03 200 hpdi help!

[phishirman]

Hey guys, new to the board here and having some issues with my Hammer. Any ideas what would cause (what I think is) the number 5 cylinder (lower left) plug to foul out extremely bad on my 03 200 HPDI?? All the other plugs look great, but that one is covered black chunky oily crud, like there's no spark at all, but I've confirmed there is. I'm only getting 5000 RPMs at WOT with the correct prop/prop height and I am seeing slight surging at mid range RPMs. Other than that, the motor starts great and idles great. Its a DOG out of the hole and I've lost about 15 MPH on top end. I've replaced all the fuel lines from the boat side all the way up to water seperator on the engine, checked my gas tank pick ups for obstructions, checked the vent screens on the tanks, replaced the bulb, replaced all the filters EXCEPT for the top microfilter or whatever it is (the pricey one) which is next on the agenda. Pulled the VST apart and replaced the filter and screen and brought it in to be pressure tested (checked out good). This was last year, but I pulled the air box off to look inside there and there was a lot of fuzzy oily residue and the top 3 intakes had a lot of oily crap in em. Compression is good on all cylinders. I'm also not seeing instantaneous throttle response. It takes about 2-3 seconds once I put the hammer down for the engine to kick in. and finally when trying to load up the boat, at WOT throttle, I can only get up to about 2500 RPMs. Occasionally it will seem like all cylinders will "kick in" and run up to 3800 or so, but I can sit there indefinitely (not that I would) with the hot foot floored and only turn about 2500 like I've got 40 pitch prop that will barely turn or something like that. any and all input is welcomed and appreciated. Ohhh. I also tried a shock treatment of ring free and run sea foam. Lastly, I'll be sending the injectors off next week for cleaning and flow testing.

[rodbolt17]

hotfoot

typically means bass boat.
can we get a model number?
the 200 HPDI was made in several versions.
most bass boat were vz the rest were z.

[snascar2424]

check spark again

I have seen spark checked outside the motor but when put under compression it take the path of least resistance. I would check the plug wire and the coil and make sure your not bleeding of energy. I have seen a small hole in the wire and you check spark everything checks, I would guess that cylinder is not getting spark under compression. The only other thing is that to much fuel is getting in that cylinder. If you can move the coil to another cylinder it might not be the fastest method but would tell you if a coil or wire is bad. good luck

[phishirman]

You are correct...its on a bass boat.

VZ200TLRB. A bad coil was was my first thought, but I swapped it with the one above it and didn't notice any difference and like I said I am getting spark....However, you may be onto something. Probably not the smartest thing to do, but I unplugged the wire from the mentioned cylinder and it runs the exact same so it seems like a spark issue... Would a faulty injector cause the plug to look like I explained?

thanks again for the replies

[99yam40]

Too much fuel or not enough fuel either way will not allow the cylinder to fire properly, as will loss of spark.

I would get it hooked up to a computer and see what is going on before you really cause some major problems

[jb123]

have you checked low pressure pumps ?

[rodbolt17]

ign coil failures on the HPDI are so rare I have never seen it.
its a 12V TCI system.
I would look at high pressure fuel rail first.
it it fails then the system is down.
typically a bad/clogged medium pressure filter or a lift pump or a VST filter.
a faulty shift position switch will mess with you.
that engine runs on 4 cylinders in N.
in N above about 1500 it drops two more.

[phishirman]

low pressure pumps have also been replaced and the VST has been gone through. I'm going to bite the bullet and bring it in to the shop to hopefully get fixed. I'll let you guys know what it was.